Not all people with OCD do this, but some surely do. They are looking for symmetry, and they have the idea that if things are not all the same or do not all look the same, something bad will happen, or they won’t be able to handle it.
In order to avoid this, they may vacuum in only one direction, make sure that their feet leave identical looking footprints on the carpet, or actually get on the floor and comb the fibers on the carpet until they are all even and going in the same direction. This can obviously take hours each day.
A documentary made about OCD in 2002, OCD: The War Inside, featured a boy who felt he had to leave all of the carpet fibers on the stairs facing the same direction, so he performed an elaborate ritual to walk up the stairs. If he made a mistake on any stair, he would have to go all the way back down to the first stair and start over again. He said that there were days that it would take him hours to walk upstairs to his room.
Why not just take the carpet off the stairs, you might ask? Although this may seem to be a quick fix, it does not address the fundamental issue, he needed therapy to learn how to face this sort of problem.
Just because he may not have carpet in his home does not mean that he will never encounter carpeting again or that the pattern of obsessive thoughts and compulsive behaviors won’t manifest itself in another way.
Therefore, his best option was to leave the carpeting there and learn how to handle it and fight the disorder, which is what happened.